Spin-Chirality Separation and S_3-Symmetry Breakings in the Magnetization Plateau of the Quantum Spin Tube

TL;DR

This paper investigates the magnetization plateau in a three-leg spin-1/2 tube, revealing how increasing leg coupling induces various phases with broken symmetries and gapless excitations, relevant to experimental observations.

Contribution

It introduces an effective chirality model combined with DMRG to analyze phase transitions and symmetry breakings in the magnetization plateau of the quantum spin tube.

Findings

Identification of chirality liquid with gapless excitations

Emergence of spin imbalance and vector-spin-chirality ordered phases

Plateau spin gap remains open during phase transitions

Abstract

We study the magnetization plateau state of the three-leg spin-1/2 tube in the strong rung coupling region, where S_3-symmetry breakings and low-energy chirality degree of freedom play crucial roles. On the basis of the effective chirality model and density matrix renormalization group, we clarify that, as the leg coupling increases, the chirality liquid with gapless non-magnetic excitations, the spin imbalance phase and the vector-spin-chirality ordered phase emerge without closing the plateau spin gap. The relevance of these results to experiments is also discussed.